package org.example;

import java.util.Scanner;

public class Test2
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        System.out.println(sqrtInt(a));
    }

    private static int sqrtInt(int a)
    {
        int i = 2;
        while (i * i <= a)
        {
            i++;
        }
        return i - 1;
    }
}
